core: add EXEC_DIRECTORY_TYPE_SHALL_CHOWN() helper

Let's make ConfigurationDirectory= a bit less "special-casey", by hiding
the fact that it's the only per-service dir we do not do chown()ing for
inside of a new EXEC_DIRECTORY_TYPE_SHALL_CHOWN() helper.

src/core/execute.h

@@ -152,6 +152,12 @@ typedef enum ExecDirectoryType {
         _EXEC_DIRECTORY_TYPE_INVALID = -EINVAL,
 } ExecDirectoryType;
 
+static inline bool EXEC_DIRECTORY_TYPE_SHALL_CHOWN(ExecDirectoryType t) {
+        /* Returns true for the ExecDirectoryTypes that we shall chown()ing for the user to. We do this for
+         * all of them, except for configuration */
+        return t >= 0 && t < _EXEC_DIRECTORY_TYPE_MAX && t != EXEC_DIRECTORY_CONFIGURATION;
+}
+
 typedef struct ExecDirectoryItem {
         char *path;
         char **symlinks;